The invention relates generally to a method for producing an ultrasound transformer having a piezoelectric transformer element and more particularly, to an ultrasound transformer having a transformer element that is coupled to an acoustical matching layer formed of an elastomer capable of vibrating, as a single, uniform body.
Methods for producing ultrasound transformers of the type mentioned above are known. For example, such a known method is disclosed in U.S. Pat. No. 4,128,370. This reference discloses a solid body ultrasound transformer in which a matching layer consisting of an elastomer is used for matching to the surrounding medium of air. When applying the elastomer to the transformer element, the latter should be held in position as precisely as possible, with respect to its outer contours or to a housing. To accomplish this positioning, the aforementioned U.S. patent provides centering elements that position the transformer element centrally with respect to the elastomer and at the proper height and plane that is parallel to the elastomer. To apply the elastomer matching layer to the transformer element, a complicated device is used, which press heats the elastomer directly onto the transformer element while under pressure, into a specially structured cavity. The pressure that is exerted is limited by a spring system which is part of the device, so that the transformer element, which is formed from a piezoceramic element, does not degrade under excessive pressure with respect to its properties such as polarization and sensitivity. The centering element used in the aforementioned method has openings, i.e. cavities, into which lead wires contacting the transformer element must be threaded before applying the matching layer. It is not possible to test the quality of the matching layer itself, which might be limited due to undesirable air inclusions, for example.
Therefore, the prior art does not provide a simple method for producing ultrasound transformers that avoids the above-mentioned disadvantages.